Double burner fuel control system



April 9, 1968 F. RIEHL. 3,376,862

' DOUBLE BURNER FUEL CONTROL SYSTEM Filed on. 2:5, 1965 2 Sheets-Sheet 1 R i 4 BU NER BURNER INVENTOR FRED RIEHL HIS ATTORNEYS April 9, 1968 F. RIEHL DOUBLE BURNER FUEL CONTROL SYSTEM 2 Sheets-Sheet Filed on. 23, 1965 Q APE LL HIS ATTORNEY$ United States Patent 0 3,376,862 DOUBLE BURNER FUEL CONTROL SYSTEM Fred Riehl, Greensbnrg, Pa., assignor to Robertsliaw Controls Company, Richmond, Va., a corporation of Delaware Filed Oct. 23, 1965, Ser. No. 503,385 13 Claims. (Cl. 126-39) ABSTRACT OF THE DISCLOSURE This disclosure relates to a pilot burner arrangement for the broil burner of a double burner oven wherein primary air is fed to the broil pilot burner by a snorkel tube having an inlet end disposed in communication with a baffle box in the lower end of the oven so that clean primary air from the bafile box will be fed through the tube to a primary air intake of the broil pilot burner disposed in offset fluid communication with the outlet end of the tube.

This invention relates to an improved fuel control system for a double burner oven as well as to improved parts for such a fuel control system or the like.

It is well known that domestic ovens and the like can be provided with a single cooking cavity having a broil burner located in the top of the oven and a bake burner located below the oven bottom.

In such prior known double burner ovens, expensive and complicated pilot burner means must be provided for the broil burner to ignite the same when the oven is utilized for broiling purposes. In particular, such prior known oven means cannot have a continuously burning pilot burner means for the broil burner because when the oven is utilized for baking purposes wherein the bake burner is ignited by its respective pilot burner means, the combustion products in the oven extinguish the broil burner pilot means whereby the extinguished pilot burner means would fill the oven with raw gas and thereby provide a hazardous and explosive condition. Therefore, such prior known double burner ovens utilized an electrical ignition system for the broil burner.

However, according to the teachings of this invention, a fuel control system is provided for such a double burner oven wherein the broil burner pilot means can maintain a continuously burning flame at all times regardless of whether the bake burner is being utilized or not.

In particular, this invention provides a pilot burner means so constructed and arranged that the same is adapted to supply primary air to the pilot burner means in such a manner that the primary air is drawn through a snorkel tube having the inlet end thereof disposed below the bake burner so that clean primary air is always supplied to the broil pilot burner means in such a manner that the combustion products in the oven will not extinguish the broil pilot burner flame.

In addition, this invention provides means for automatically compensating for air pressure changes in the oven adjacent the broil pilot burner means during rapid opening and closing of the oven door to prevent outages of the broil pilot burner means.

In particular, this invention provides a bafile box construction receiving the inlet end of the snorkel tube of the broil pilot burner means and acts in a manner hereinafter described to equalize the pressure differential at the broil pilot burner means during rapid opening and closing of the oven door so that the pilot flame is not extinguished.

Accordingly, it is an object of this invention to provide an improved fuel control system for a double burner oven or the like, the system of this invention having one 3,376,862 Patented Apr. 9, 1968 or more of the novel features set forth above or hereinafter shown or described.

Another object of this invention is to provide an improved pilot burne-r means having one or more of the novel features set forth above or hereinafter shown or described.

A further object of this invention is to provide an improved baffle box construction having one or more of the novel features set forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIGURE 1 is a fragmentary front view schematically illustrating the double burner oven of this invention.

FIGURE 2 is a fragmentary cross-sectional view taken on line 2-2 of FIGURE 1.

FIGURE 3 is a fragmentary cross-sectional view taken on line 3-3 of FIGURE 2.

FIGURE 4 is an enlarged, fragmentary cross-sectional view taken on line 4-4 of FIGURE 1.

FIGURE 5 is a fragmentary top view of the structure illustrated in FIGURE 4 with various parts thereof in cross section.

FIGURE 6 is a fragmentary cross-sectional view taken on line 6-6 of FIGURE 5.

- FIGURE 7 is a fragmentary view similar to FIGURE 5 and illustrates the use of a detachable restrictor for the pilot burner means of this invention.

FIGURE 8 is a perspective view of the restrictor utilized in FIGURE 7.

While the various features of this invention are hereinafter shown and described as being particularly adaptable for use in a domestic double burner oven, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof in any other fuel control system or the like.

Therefore, this invention is not to be limited to only the embodiments illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention.

Referring now to FIGURE 1, the improved fuel control system of this invention is generally indicated by the reference numeral 10 and comprises a double burner oven 11 having a rear wall 12 and carrying a broil burner means 13 and a bake burner means 14 with the bake burner means 14 being disposed below the bottom wall means 15 of the oven 11.

Fuel is adapted to be thermostatically and selectively supplied to either the bake burner means 14 or the broil burner means 13 in any conventional manner for baking purposes or broiling purposes as desired, the temperature of the oven 11 being sensed by a temperature sensing bulb 16 to control the fuel control system in the conventional manner.

The fuel issuing from the bake burner means 14 is adapted to be ignited by conventional pilot burner means 17 in a conventional manner.

However, when fuel issued from the broil burner means 13, the same is adapted to be ignited by a continuously burning pilot burner means 18 of this invention in a manner hereinafter described.

As previously stated, the fuel control system 10 of this invention permits the broil pilot burner means 18 of this invention to have a continuous flame even though th broil burner 13 is not being utilized and the bake burner means 14 is being utilized with any adverse effect on the broil pilot burner means 18 due to the combustion by-products in the oven 11.

In particular, the broil pilot burner means 18 is adapted to be supplied with clean primary air by means of a snorkel tube 19 having an outlet end 20 interconnected to the pilot burner means 18 in a manner hereinafter described and an inlet end 21 disposed below the bake burner means 14.

In addition, it has been previously stated that the fuel control system 10 of this invention maintains a continuously burning flame at the broil pilot burner means 18 even though the oven door (not shown) is rapidly opened and closed and, thus, causing momentary air pressure changes at the broil pilot burner means 18 which would normally extinguish the flame at the pilot burner means 18.

However, such pressure changes at the pilot burner means 18 is compensated for by a baflle box construction 22 of this invention in a manner hereinafter set forth.

As illustrated in FIGURES 4-6, the broil pilot burner means 18 includes a housing means 23 adapted to be secured to a mounting member 24 on the oven wall 12 by suitable fastening means 25.

The housing 23 has a transverse bore 26 interrupting one side 27 thereof and terminating at an end wall 28. Another bore 29 interrupts the end 30 of the housing 23 and intersects the bore 28 for a purpose hereinafter described.

A cylindrical conduit 31 has one end 32 thereof received in the bore 29 of the housing 23 and is secured therein in any suitable manner.

The other end 33 of the conduit 31 is beveled in the manner illustrated in FIGURE 4 and is secured in any suitable manner to a substantially inverted U-shaped and angled hood or flame shield 34 having a bottom wall 35 disposed at an angle relative to the horizontal.

The opposed side walls 36 of the hood 35 have aligned apertures 37 passing therethrough and respectively receiving a fiame sensing bulb 38 having an end 29 abutting against an integral tang 40 formed from one of the sides 36 of the hood 34. The bulb 38 is held in the position illustrated in FIGURE 5 by a threaded set screw 41 threadedly carried by a bracket means 42 attached to the hood 34.

The bulb 38 is so constructed and arranged that as long as the bulb 38 senses a pilot flame 43 in the manner illustrated in FIGURE 4, a suitable fuel safety valve is adapted to be held in the open position so that when the fuel selector means of the system 10 of this invention is set in its broil position, fuel is adapted to issue from the broil burner means 13 and be ignited by the flame 43 at the pilot burner means 18. However, should the flame 43 of the pilot burner means 18 be extinguished, the flame sensing bulb 38 causes the safety valve to remain in its closed position in a conventional manner whereby fuel cannot issue to the broiler burner means 13 even though the conventional selector valve of the fuel control system is set in its broil position.

The housing 23 of the pilot burner means 18 has the other end 44 thereof interrupted by a bore 45 coaxial and interconnecting with the conduit 31. The end 44 of the housing 23 is externally threaded at 46 and receives an orifice cup 47 in the bore 45. A fuel supply line 48 is coupled to the orifice cup 47 by a fastening collar 49 threaded on the threaded part 46 of the housing 23 whereby fuel being supplied by the fuel conduit 48 is adapted to pass into the conduit 31 through an orifice 50 formed in the closed end 51 of the orifice cup 47.

A tubular adapter 52 has one end 53 secured in the bore 28 of the housing 23 and is adapted to telescopically receive the outlet end 20 of the snorkel tube 19. The adapter 52 can be provided with a suitable threaded opening 54 for securely fastening the outlet end 20 of the tube 19 therein by a suitable set screw or the like.

The conduit 31 of the pilot burner means 18 has a primary air intake 55 cut therein to interconnect with a chamber 55A formed in th housing 23 by the bore 26 and completely surrounding the conduit 31 at the air intake 55 thereof.

However, the air intake 55 is formed in the conduit 31 in such a manner that the air intake 55 is disposed substantially at from the outlet end 20 of the snorkel tube 19 whereby the conduit 31 baflles the flow of primary air to the air intake 55 for a purpose hereinafter described.

While the pilot burner means 18 illustrated in FIGURE 5 has been designed to be utilized with natural gas, the pilot burner means 18 can be converted for use with manufactured or butane air gases by utilizing a restrictor 56 of this invention illustrated in FIGURE 8 and utilized in the manner illustrated of FIGURE 7.

In particular, the restrictor 56 comprises a disc like member 57 having a restricting orifice 58 passing therethrough and having detent legs 59 on the outer periphery thereof so that the restrictor 56 can be disposed in the adapter 52 in the manner illustrated in FIGURE 7 to be disposed between the outlet end 20 of the snorkel tube 19 and the air intake 55 of the conduit 31 to restrict the flow of primary air passing to the air intake 55 from the snorkel tube 19.

As previously stated, the inlet end 21 of the snorkel tube 19 is received in a baflle box construction 22 located in the lower end of the oven 11.

In particular, the baifle box construction 22 comprises a substantially U-shaped metal member 60 having outwardly turned ends 61 on the legs 62 thereof with the outwardly turned ends 61 being secured to the rear wall 12 of the oven 11 by suitable fastening means 63 whereby the rear of the U-shaped member 60 is closed by the rear wall 12 of the oven 11.

The baffle box construction 22 of this invention has an upper open end 64 received in the hollow bottom wall means 15 of the oven 11 in the manner illustrated in FIG- URES 1 and 2 while a lower open end 65 of the battle box construction 22 extends into the lower part of the burner box 66 of the oven 11 below the bake burner means 14.

A pair of baflle members 67 are respectively carried by the opposed legs 62 of the baflie box construction 22 and extend across the complete depth thereof and across more than half the width thereof while being in spaced and overlapping relation in the manner illustrated in FIG- URE 1 to provide a tortuous path for the clean primary air entering the open lower end 65 of the baffie box construction 22 before the same reaches the inlet end 21 of the snorkel tube 19, the inlet end 21 of the snorkel tube 19 passing through a suitable aperture 68 formed in one of the legs 62 of the U-shaped member 60 at a point above the baflle means 67 but below the bake burner means 14.

Therefore, it can be seen that the various parts of the fuel control system 10 of this invention are relatively simple to manufacture while operating in an improved manner now to be described.

When the oven 11 is installed and adjusted, the fuel control means is so constructed and arranged that fuel is adapted to be continuously supplied by the conduit means 48 to the pilot burner means 18 whereby the fuel issuing from the pilot burner means 18 is initially ignited so that a continuously burning flame 43 will be produced at the pilot burner means 18.

As previously stated, the broil pilot burner means 18 maintains the flame 43 for subsequently igniting fuel issuing from the broil burner means 13 when the broil burner means 13 is turned on even though previously the oven 11 was utilized for baking purposes wherein the bake burner 14 was utilized and ignited by the bake pilot burner means 17 causing combustion by-products in the oven 11 to surround the pilot burner means 18.

The pilot burner means 18 is so constructed and arranged in the manner previously set forth that the same is adapted to entrain adequate primary air by the superior injection means of this invention to have the flame 43 burn in the environments of the by-product produced by the bake burner means 14 and the pilot burner means 18 does not have outages even after the oven is heated and the oven door is opened to cause excessive primary air entrainment induced by the stacked effect of the hot snorkel tube 19 supplying primary air to the pilot burner means 18.

Further, the pilot burner means 18 of this invention is so constructed and arranged that the same entrains a maximum of primary air during the oven heat up period and is able to tolerate excessive primary air entrainment after heat up when the door is opened, without pilot flame outage, while using the various gases and pressures encountered in the field.

In particular, it can be seen that the inlet end 21 of the snorkel tube 19 is disposed below the bake burner means 14 whereby clean primary air is adapted to be drawn upwardly through the lower open end 65 of the baffle box construction 22 and enter inlet end 21 of the snorkel tube 19 and be drawn into the chamber 55A of the pilot burner means 18 by the Venturi effect produced by the flow of fuel passing from right to left through the conduit 31 of the pilot burner means 18. Thus, the clean primary air from the chamber 55A is drawn into the air intake 55 and is mixed with the fuel passing through the conduit 31 whereby the air fuel mixture is traveled in a straight path to the outlet end 33 of the conduit 31 and targeted at the source of burning 43 in the hood or shield 34. The distance from the outlet end 33 of the conduit 31 and the configuration of the hood 34 are so constructed and arranged to provide stability to the pilot flame 43.

As previously stated, the air intake 55 of the conduit 31 is exposed approximately 180 from the snorkel tube outlet whereby this arrangement permits adequate primary air to be entrained in the fuel passing through the conduit 31 while the conduit 31 itself baffles the flow of air from the snorkel tube 19 to the air intake 55 to prevent irregular and sudden air gusts which would break the gas stream in the conduit 31 and cause pilot outage, i.e., without the particular conduit 31 and snorkel tube arrangement 19 of this invention, the flame 43 of the pilot burner means 18 would go out after the oven is heated and the oven door is opened causing an excessive entrance of primary air through the heated snorkel tube 19 and impairing the orifice injection and gas mixture. 1

The pilot hood design 34 is so constructed and arranged that the bottom wall 35 thereof has a triangular opening 69 which permits the available secondary air in the oven 11 to be utilized for combustion during oven heat up.

This pilot burner arrangement 18 produces a hard target flame 43 with a low pilot rate. The location of the target flame 43 from the pilot conduit 31 relieves the back pressure in the mixer conduit 31 whereby the entrainment of primary air is increased along with pilot stability under contaminated air operating conditions.

While the broil pilot burner means 18 illustrated in FIGURE 5 is os constructed that the same provides adequate primary air for natural gas, the snorkel tube arrangement 19 is readily convertible to be utilized with manufactured or butane air gases by utilizing the restrictor 56 previously described in the manner illustrated in FIGURE 7 whereby the flow of primary air supplied by the snorkel tube 19 is reduced to the correct amount.

Therefore, it can be seen that the broil pilot burner means 18 is adapted to maintain a continuous flame 43 in the oven 11 even though the bake burner means 14 is being utilized and contaminating the atmosphere in the oven 11 by combustion by-products and the like.

When the oven door is rapidly opened, the same causes a substantial but momentary air pressure decrease adjacent the pilot burner means 18 whereby the snorkel tube 19 would tend to oversupply primary air through the conduit 31 and thereby cause flame outage.

However, when the oven door is rapidly opened causing a momentary and substantially reduced air pressure in the oven 11, such reduced air pressure is also caused in the bottom wall means 15 whereby the air pressure in the battle box construction 22 is correspondingly reduced to reduce the amount of primary air pressure being supplied to the pilot burner means 18 because the baffle means 67 prevent an immediate rush of air into the baflle box construction 22 to the inlet end 21 of the snorkel tube 19.

Conversely, when the oven door is rapidly closed, a momentary but substantial increase in air pressure is provided in the oven 11 which would tend to retard the flow of fuel to the flame area 43 of the pilot burner means 18 and cause a pilot outage. However, as the air pressure is momentarily increased in the oven 11 by the rapid closing of the oven door, the air pressure in the bottom wall means 15 is correspondingly increased and forced through the upper open end 64 of the bafille box construction 22 into the inlet end 21 of the snorkel tube 19 and, thus, to the pilot burner means 18 to compensate for such increased air pressure at the pilot burner means 13 to prevent pilot outage, the baffle means 67 momentarily preventing the increased flow of air into the upper end 64 of the bafile box construction 22 from escaping out of the lower open end 65 thereof.

Thus, it can be seen that while the rapid opening and closing of the oven door tends to create an unbalanced air. pressure condition between the pilot burner means 18 and the location of the primary air intake 21 in the burner compartment 66, the baille box construction 22 of this invention equ-alizes the pressure differentiatial by diverting the air being forced out of the even up the snorkel tube 19 so that a balance is achieved and the pilot flame 43 is not extinguished.

Accordingly, it can be seen that this invention not only provides an improved fuel control system for a double burner oven or the like, but also this invention provides an improved pilot burner means and baffle box construction for such a fuel control system or the like.

While the form of the invention now preferred has been disclosed as required by statute, other forms may be used, all coming within the scope of the claimed subject matter which follows.

What is claimed is:

1. In a fuel control system for a double burner oven, the improvement comp-rising a pilot burner for igniting the upper broil burner, means for continuously supplying fuel to said pilot burner, and a snorkel tube having an outlet interconnected to said pilot burner and an inlet disposed below the bake burner to supply clean primary air to said pilot burner, said oven carrying means for balancing the air pressure at said pilot burner during opening and closing of the oven door to prevent outage to said pilot burner due to the change in air pressure in said oven caused by opening and closing said oven door, said last-named means comprising a battle box receiving said inlet end of said tube.

2. In a fuel control system as set forth in claim 1, said bafile box having a lower open end for receiving said clean air and delivering the same to said inlet end of said tube.

3. In a fuel control system as set forth in claim 2, said baflle 'box carrying at least two olfset baffle plates at said lower end thereof to cause a tortuous path for the air entering said lower end of said box to said inlet end of said tube.

4. In a fuel control system as set forth in claim 3, said bafie box having an upper open end such that when said oven door is rapidly opened to reduce the air pressure at said pilot burner the air pressure at the top of said box is likewise reduced whereby said baflies prevent an increased flow of primary air to said pilot burner and when said oven door is rapidly closed to increase the air pressure at said pilot burner the air pressure at the top of said box is likewise increased whereby said baflies divert said increased air flow at said top of said box into said inlet end of said tube.

5. In a fuel control system as set forth in claim 1, said pilot burner air intake disposed offset relative to said outlet end of said tube.

6. In a fuel control system as set forth in claim 5, said pilot burner having a conduit leading from said fuel supply means to a pilot flame area With said conduit having said air intake formed therein substantially at right angles relative to the fuel flow through said conduit.

7. In a fuel control system as set forth in claim 6, said pilot burner defining a chamber surrounding conduit at said air intake, said outlet end of said tube entering said chamber at 180 from said air intake.

8. In a fuel control system for a double burner oven, the improvement comprising a pilot burner for igniting the upper broil burner, means for continuously supplying fuel to said pilot burner, and a snorkel tube having an outlet interconnected to said pilot burner and an inlet disposed below the bake burner to supply clean primary air to said pilot burner, said pilot burner having a primary air intake disposed olfset relative to said outlet means of said tube, said pilot burner having a detachable restrictor between said air intake and said outlet end of said tube.

9. A pilot burner means having a fuel flow directing conduit structure having an inlet end and an outlet end, said structure having a primary air intake intermediate said inlet and outlet ends for receiving primary air and directing the same into said flowing fuel, said structure having a coupling means for receiving the outlet end of a primary air snorkel tube, said coupling means telescopically receiving said conduit structure and seperating said intake externally from said inlet and outlet ends of said conduit structure, said structure being so constructed and arranged that said air intake is offset relative to said outlet end of said tube while being in communication therewith.

10. A pilot burner means as set forth in claim 9 wherein said structure includes a conduit leading from a fuel supply means to a pilot flame area with said conduit having said air intake formed therein substantially at right angles relative to the fuel flow through said conduit.

11. A pilot burner means as set forth in claim 10 wherein said structure defines a chamber surrounding said conduit at said air intake and wherein said coupling means interconnects said outlet end of said snorkel tube to said chamber at 1 80 from said air intake.

12. A pilot burner means having a fuel flow directing structure, said structure having a primary air intake for receiving primary air and directing the same into said flowing fuel, said structure having a coupling means for receiving the outlet end of a primary air snorkel tube, said structure being so constructed and arranged that said air intake is offset relative to said outlet end of said tube while being in communication therewith, said structure carrying a detachable restrictor between said air intake and said outlet end of said snorkel tube.

13. A pilot burner means as set forth in claim 9 wherein said structure includes a flame shield having a secondary air supply opening therein, said shield carrying a flame sensing bulb.

25 References Cited UNITED STATES PATENTS 1,302,914 5/1919 Goreau 158-115 1,987,618 1/1935 Grayson 158-115 X 30 2,761,497 9/1956 Munn 158-115 2,880,717 4/1959 Tilmann 126-110 3,308,871 3/1967 Riehl 158-115X 3,315,655 4/ 1967 Stone et a1. 158-115X 3 3,320,943 5/1967 Crannell et al. 126-39 0 FREDERICK L. MATTESON, IR., Primary Examiner.

E. G. FAVORS, Assistant Examiner.

Disclaimer 3,376,862.-Fr0d Riehl, Greensburg, Pa. DOUBLE BURNER FUEL CON- TROL SYSTEM. Patent dated Apr. 9, 1968. Disclaimer filed Sept. 21, 1970, by the inventor and the assignee, Robertshaw Controls Company. Hereby enter this disclaimer to claims 1 and 2 of said patent.

[Oflicial Gazette Jwne 15, 1971.] 

